1. Field of the Invention
The present invention relates to an electric rotating machine, for a vehicle or the like, that is coupled with an engine, and particularly to the structure thereof.
2. Description of the Related Art
To date, there has been disclosed an in-vehicle AC generator in which there are formed two slots for each polarity and each phase in a stator iron core configured of laminated magnetic thin plates, and a set of U-phase, V-phase, and W-phase windings is configured with phase windings formed of coil conductors inserted in the slots (e.g., refer to Japanese Patent Application Laid-Open No. 2002-354736).
In a conventional in-vehicle AC generator disclosed in Japanese Patent Application Laid-Open No. 2002-354736, a set of U-phase, V-phase, and W-phase windings is formed by connecting in series respective phase windings whose phases are different from one another by an electric angle of 30° by means of outgoing leads for phase-to-phase connection provided at the respective ends of the phase windings. These phase windings are connected with one another by means of neutral-point outgoing leads, so that a set of Y-connected three-phase AC armature windings is configured.
In a conventional in-vehicle AC generator configured in such a way as described above, each of the outgoing leads for connecting the phase windings in series with one another is pulled out from the end of the corresponding phase winding and disposed on the coil end of the corresponding phase winding; similarly, the neutral-point outgoing lead is also disposed on the coil end of the corresponding phase winding.
Additionally, to date, there has been disclosed an in-vehicle electric rotating machine in which the high-potential switching elements out of switching elements that are included in an electric-power conversion device are fixed to a high-potential heat sink and the low-potential switching elements are fixed to a low-potential heat sink, and the switching elements are cooled by use of these heat sinks (e.g., refer to Japanese Patent Application Laid-Open No. 2008-5678).
The conventional in-vehicle electric rotating machine disclosed in Japanese Patent Application Laid-Open No. 2008-5678 is configured in such a way that a battery terminal is provided in the high-potential heat sink for each phase, and in accordance with the mounting situation of the electric rotating machine, selection of the battery terminals can be performed. Furthermore, outgoing leads are drawn from the switching elements, diodes, and the like for connecting them with the armature winding.
In general, in an in-vehicle electric rotating machine, the shorter the lengths of the phase-to-phase connection outgoing lead and the neutral-point outgoing lead are, the smaller the risk of breakage of the outgoing leads becomes and the higher the reliability of the electric rotating machine becomes. The arrangements and the lengths of the phase-to-phase connection outgoing leads and the neutral-point outgoing leads change depending on the outgoing positions of the outgoing leads from the switching elements and the diodes and on the number of phases of the armature winding; therefore, in order to reduce the lengths of the phase-to-phase connection outgoing leads and the neutral-point outgoing leads, it is required to make the positions of the outgoing leads from the switching elements and the diodes to be concentrated.
Meanwhile, in the case where an electric-power conversion device is operated as an inverter and an electric rotating machine is utilized as a motor for driving a vehicle, a large armature current for producing large torque flows into switching elements, whereby a large amount of heat is generated in the switching elements. Accordingly, in terms of effective cooling of the switching elements, it is advantageous to arrange the heat sinks to which the switching elements are fixed, in such a way as to be dispersed around the center axis of the electric rotating machine.
Accordingly, in a conventional in-vehicle electric rotating machine, it has been difficult to strike a good balance between shortening the phase-to-phase connection outgoing leads and the neutral-point outgoing leads and effectively cooling the switching elements. In other words, in the case where, in order to shorten the phase-to-phase connection outgoing leads and the neutral-point outgoing leads, the switching elements are arranged in a concentrated manner, the electric rotating machine becomes high-temperature due to the concentration of the switching elements that become high-temperature in a narrow space. In contrast, in the case where, in order to effectively cool the switching elements, the heat sinks to which the switching elements are fixed are arranged in a dispersed manner around the center axis of the electric rotating machine, the positions of the outgoing leads for connecting the switching elements and the diodes are dispersed; as a result, the lengths of the phase-to-phase connection outgoing leads and the neutral-point outgoing leads become large, whereby the risk of the breakage of these outgoing leads is enlarged.